Partially-fluorinated polymers

ABSTRACT

Partially fluorinated polymer comprising a backbone and side-chains, in which the backbone and side-chains are each 4 atoms long and are chemically incompatible, one chain being at least predominantly hydrocarbon and the other comprising a C 4+  perfluorocarbon moiety.

This invention relates to partially-fluorinated polymers that have chemically-incompatible segments; the polymers have interesting and varied properties, including liquid crystallinity.

An example of a molecule having two distinct parts that are mutually-immiscible is C₁₀ H₂₁ --C₁₀ F₂₁, i.e. (perfluorodecyl)decane, as described by Twieg, Robolt J. Polym. Sci. Polym. Phys. Ed. 21:901(83), and Mahler, Guillon and Skoulios, Mol. Cryst. Liq. Cryst. 2:111-119 (1985). That compound was prepared by the reaction of perfluorodecyl iodide with 1-decene, followed by reduction; the amphiphilic product exhibited a smectic B liquid crystalline phase.

Hopken et al, "Integration of Fundamental Polymer Science Technology--5", ed. Lemstra and Kleintjes, Elsevier Applied Sciences, describe amphiphilic allyl ethers and methacrylates. Alcohols of the formula F(CF₂)_(n) (CH₂)_(m) OH, wherein n=8, 10, 12 and m=4, 6, 10, were converted to allyl ethers, and sequentially perfluorinated methacrylates were then prepared. The polymers exhibit a mesomorphic "Schlieren" texture.

Budovskaya et al, Polymer Science USSR 32 (3):502-506 (1990), disclose comb-like polyfluoroalkyl (meth)acrylates having side-chains of the formula═COOCH₂ (CF₂)_(n) H, wherein n=2, 4, 6, 8, 10, 12; the backbone comprises a single --CH₂ -- group between the carbonate and the CH or CCH₃ group to which the side-chains are bonded. The polymers are mesomorphic in structure, with a degree of ordering directly related to n; for n=10, the formation of a liquid crystal state "is proved by an optical method".

EP-A-0352718 discloses partially-fluorinated polymers in which repeating units include a sequence of the formula

    --X.sub.1 --CH.sub.2 CH.sub.2 --R.sub.f --CH.sub.2 CH.sub.2 --X.sub.2 --

wherein X₁ and X₂ are polymer-forming linkages (e.g. COO or OOC for polyesters, CONH or NHCO for polyamides) and R_(f) is a C₁₋₄₀ perfluorinated divalent organic radical. Such polymers are prepared from dinitriles or ester-nitriles. The polymers are apparently those sold under the registered Trade Mark "Zonyl" as fluoro-surfactants that offer thermal and chemical stability superior to that of hydrocarbon surfactants. The polymers are also suitable for use as non-stick coatings.

Surprisingly, it has now been found that polymers having chemically-incompatible segments can be produced that clearly have liquid crystalline properties, as well as offering the properties associated with the polymers described above. The repeating units (of which there may be any number, preferably at least 3, e.g. 3 to 30) of the novel polymers include a side-chain and, between the atom or group to which the side-chain is bonded, a backbone chain: the chains are each at least 4 atoms long and are chemically-incompatible, one chain being at least predominantly hydrocarbon and other comprising a C₄₊ perfluorocarbon group. Depending on which of the chains comprises the hydrocarbon and perfluorocarbon groups, representative formulae of repeating units of polymers according to the present invention are

    --X.sup.1 --hc.sup.1 --Z(hc)--hc.sup.2 --X.sup.2 --fc--

    --X.sup.1 --hc.sup.1 --Z(fc)--hc.sup.2 --X.sup.2 --hc--

wherein X¹ and X² are as defined above; Z is the atom or group to which the side-chain is bonded; fc is the perfluorocarbon; and hc, hc¹ and hc² are each hydrocarbon (hc may also be replaced by a perfluorocarbon group fc¹ that is the same or different from fc).

The atom or group to which the side-chain is bonded, i.e. Z in the formulae given above, may be --CH(--)-- or --CH(CH₂ --)--, but is preferably --N(SO₂ --)--; the bracketed hyphen indicates attachment of the side-chain. The preference for --N(SO₂ --)-- reflects a preferred process for introducing the side-chain into one of the monomers from which a polymer may be prepared. Thus, for example, the compound fcSO₂ F is reacted with a compound of the formula

    Y.sup.1 --hc.sup.1 --ZQ--hc.sup.1 --Y.sup.1

wherein Q is a reactive group and Y¹ is a group reactive with another group Y² to form X¹ or X² in the ultimate polymer. Y¹ is a substituent such as I or OH, or within hc¹ or hc², e.g. a C═C bond. In this case, when the side-chain comprises the perfluorocarbon group, the relevant monomer can be synthesised without forming a carbon--carbon bond and without the expense of obtaining or synthesising the appropriate perfluoroalkyl iodide (fcI).

Although the monomers and polymers to which this invention relates may be prepared by procedures that will be readily apparent to those skilled in the art, polyesters of the invention may be prepared by the Stupp method of ester formation, following Moore et al, Macromolecules 23:55-70 (1990). This procedure, and the invention as a whole, are illustrated in the following Examples. The reaction scheme is shown in the Chart headed "Fluorinated Side-chain Polyesters".

EXAMPLES 1 TO 10

In each case, the compound shown in the Chart as "F₈ " and "C1" in the following table of properties was reacted with a different hydrocarbon dicarboxylic acid, to obtain the polymer enumerated as 2-11 in the tabulated data. More specifically, in each case, 0.587 g of "F₈ " was stirred with a stoichiometric amount of the dried diacid in approx. 50 ml dry CH₂ Cl₂ (all reagents were dried), and 0.19 g PTSA and 0.122 g DMAP were added together. Then 0.8-1.2 ml diisopropylcarbodiimide was added to the stirred solution under a positive stream of N₂.

PTSA=paratoluenesulphonic acid

DMAP=4-dimethylaminopyridine

After a few hours, a white precipitate formed. After 1 day, the product was precipitated by pouring the solution into a larger volume of methanol (approx. 150-200 ml), and the polymer was collected by filtration. The product was washed several times with methanol to remove PTSA/DMAP.

IR spectra show ester, --C--F and --C--H. Main peaks at approx. 1730, 1100-1250 and 2800-3000. H NMR shows N--CH₂ CH₂ --O at: one multiplet 4.30(2), 2 multiplets 3.85(1), 3.65(1) and aliphatic diester between 2.8 and 1.2 (aromatic at approx. 8.0 and 7.5). Yield: usually between 80-88% white solid. See table for details. All the polymers exhibited liquid crystalline properties.

    __________________________________________________________________________                   SIDE-                                                                          CHAIN                                                            COMPOUND               NMR                                                     (Method)               H                                                       (Yield)                (in CDCl.sub.3                                          Elem. analysis         unless  NMR        DSC                                  Calc   Found  IR       ethium stated)                                                                         C   GPC    (MP, °C.)                                                                     MICRS                          __________________________________________________________________________     C1                                                                               HO-Et-N-Et-OH                                                                              3200-3400                                                                               in (CD3)2CO        (MP   LC                               SO2                  4.35t(1)           113.5-                                                                               shows                            (CF2)8      1060-1290 br.s                                                                          3.83t(2)           115.5)                                                                               wave of                          F           1616, 1580.                                                                             3.75m(1)                 batonets                                              3.64m(1)                 sweep                                                                          across                           (from 3M)                                     then                             % H  1.70  1.64                               grainy-                          % C 24.50 24.54                               thready                          % N  2.39  2.43                               texture.                       2 (OCH2CH2)2NSO2                                                                             1602, 841, 748                                                                          8.03, 8.06 d2                                                                              Insol  215, 253                                                                             Has LC                           --(CF2)8F            7.54, 7.58 d2                                                                              (Lo MW H1    phase,                           OCPhPhCO--)n                                                                               1716                 fract, in                                                                             220, 257                                                                             fluid                                        1787     4.62 m2     CHCl3) H2    birefr.                                               3.90 m2            251, 165                               (Stupp)     1060-1300br.s        Mn > 3000                                                                             C1                                     (96%)       1154, 1205                                                                              (weak, low sol)                                                                            Mw >   (255-7)                                                     (Lo MW fract)                                                                              10,000                                                    2985-2833                                                                      1450, 1388                                                       3 (O-Et-N-Et-O-                                                                              3000-2850                                                                               4.42 m2     sol    (Softng                                                                              LC Phase                         SO2                  3.94 m1     DP 12  92    small                            (CF2)8      1737 s   3.74 m1            MP 120-                                                                              thready                          F           1650                 Mn 7850                                                                               123)  texture.                         --OCCH2CH2CO--)n     2.77 s2     Mw 12000                                                                              75,133                                                                               fluid                                        1060-1290 br.s              H1    when                                         1525, 1396, 1054,    D 1.52 132, 136                                                                             opaque.                          (Stupp)     983                         H2                                     (71%)                                   130, 132                                                                       C1                                     % H  1.79  1.90                                                                % C 28.7 28.86                                                                 % N  2.09  2.26                                                              4 (O-Et-N-Et-O-                                                                              3000-2850                                                                               4.30 m2     DP 8   (MP 111-                                                                             L.C fluid                        SO2                  3.84 m1            113)  when                             (CF2)8      1737 s   3.61 m1     Mn 5400                                                                               61,111                                                                               opaque.                          F           1650                 Mw 8600                                                                               H1    Grainy                           --OC(CH2)3-CO--)n    2.41 s2            110 H2                                                                               texture                                      1060-1290 br.s                                                                          1.97 m1     D 1.59 109 C1                                             1525, 1396, 1054,                                                  (Stupp)     983                                                                (81%)                                                                        5 (O-Et-N-Et-O-                                                                              3000-2850                                                                               4.28 t2     DP 23  (MP 82-                                                                              L.C.                             SO2                  3.83 m1            84)   Birefr.                          (CF2)8      1737 s   3.62 m1     Mn 15600                                                                              66, 74.8,                                                                            fluid.                           F           1650                 Mw 24300                                                                              81 H1 Grainy                           --OC(CH2)4--CO--)n   2.36 t2            75.4 H2                                                                              texture.                                     1060-1290 br.s                                                                          1.65 m2     D 1.56 73.5 C1                                (Stupp)     983                                                                (86%)                                                                          % H 2.29  2.26                                                                 % C   31 31.24                                                                 % N 2.01  1.94                                                               6 (O-Et-N-Et-O-                                                                              3000-2850                                                                               4.28 t2            (Flexible                                                                            V. little                        SO2                  3.81 m1            glass at                                                                             birefr.                          (CF2)8      1737 s   3.64 m1            RT    Has                              F           1650                        MP 60-                                                                               (faint)                          --OC(CH2)5--CO--)n   2.33 t2            65° C.)                                                                       grainy                                       1060-1290 br.s                                                                          1.64 m2                  texture.                                     1525, 1396, 1054,                                                                       1.34 m1                  L.C fluid                        (Stupp)     983                               when                             (84%)                                         opaque.                        7 (O-Et-N-Et-O-                                                                              3000-2850                                                                               4.30 t2            (MP 70-                                                                              A little                         SO2                  3.81 m1            72)   birefr.                          (CF2)8      1737 s   3.65 m1                  Has                              F           1650                              (faint)                          --OC(CH2)6--CO)--)n  2.32 t2                  grainy                                       1060-1290 br.s                                                                          1.58 m2                  texture.                                     1525, 1396, 1054,                                                                       1.32 m2                  L.C fluid                        (Stupp)     983                               when                             (86%)                                         opaque.                        8 (O-Et-N-Et-O-                                                                              3000-2850                                                                               4.31 t2            (Softn                                                                               A little                         SO2                  3.84 m1            87    birefr.                          (CF2)8      1737 s   3.65 m1            MP 130-                                                                              Has                              F           1650                        132)  (faint)                          --OC(CH2)8--CO--)n   2.35 t2                  grainy                                       1060-1290 br.s                                                                          1.62 m2                  texture.                                     1525, 1396, 1054,                                                                       1.32 m4                  L.C fluid                        (Stupp)     983                               when                             (86%)                                         opaque.                        9 (O-Et-N-Et-O-                                                                              3000-2850                                                                               4.26 t2            (Softn                                                                               A little                         SO2                  3.85 m1            92    birefr.                          (CF2)8      1737 s   3.66 m1            MP 139-                                                                              Has                              F           1650                        141)  (faint)                          OC(CH2)12--CO--)n    2.33 t2                  grainy                                       1060-1290 br.s                                                                          1.61 m2                  texture.                                     1525, 1396, 1054,                                                                       1.25 m8                  L.C fluid                        (Stupp)     983                               when                             (86%)                                         opaque.                          % H 3.95  4.01                                                                 % C 38.6 38.52                                                                 % N 1.73  1.70                                                               10                                                                               (O-Et-N-Et-O-                                                                              3000-2850                                                                               4.28 t2            (Softn                                                                               A little                         SO2                  3.83 m1            107   birefr.                          (CF2)8      1737 s   3.64 m1            MP 129-                                                                              L.C fluid                        F           1650                        131)  when                             OC(CH2)20--CO--)n    2.31 t2                  opaque.                                      1060-1290 br.s                                                                          1.60 m2                  Has                                          1525, 1396, 1054,                                                                       1.23 m16                 grainy                           (Stupp)     983                               texture                          (88%)                                         also a                                                                         second                                                                         phase.                                                                         `needles`                      due to                                                                                                                         hydro-                                                                         carbon.                        11                                                                               (--CH2CHCO2--)n                                                                            1604, 1509, 840                                                                         Insol       Insol                                         (CH2)6-OPhCO2--                         (No MP                                 (CH2)10(CF2)12F                                                                            1730,                       Decomp.                                            1716                        >282)                                              1260                                                               (Stupp)                                                                        (64%)       1100-1280 br.s                                                                 1110, 1150, 1210                                                 __________________________________________________________________________      ##STR1## 

We claim:
 1. A polymer whose repeating units include a side-chain and, between the atoms or group to which the side-chain is bonded, a backbone chain, in which said backbone and side chains are each at least four atoms long and are chemically incompatible, one chain being at least predominantly hydrocarbon and the other comprising a C₄₊ perfluorocarbon group.
 2. A polymer according to claim 1, wherein the repeating units have the formula

    --X.sup.1 --hc.sup.1 Z(hc)--hc.sup.2 --X.sup.2 --fc--

wherein X¹ and X² are absent or are polymer-forming linkages; Z is the atom or group to which the side-chain is bonded; fc is the perfluorocarbon; and hc, hc¹ and hc² are each hydrocarbon.
 3. A polymer according to claim 1, wherein the side-chain is the perfluorocarbon group.
 4. A polymer according to claim 3, wherein the repeating units have the formula

    --X.sup.1 --hc.sup.1 Z(fc)--hc.sup.2 --X.sup.2 --hc--

wherein X¹, X² are absent or are polymer forming linkages, Z is the atom or group to which the side chain is bonded, fc is the perfluorocarbon group, hc, hc¹ and hc² are each hydrocarbon moieties of which hc may be replaced by another perfluorocarbon fc¹.
 5. A polymer according to claim 4, wherein hc¹ and hc² are each --(CH₂)₁₋₂ --.
 6. A polymer according to claim 4, wherein Z is selected from the group consisting of --N--(SO₂ --)--, --CH(--)-- and --CH(CH₂ --)--, the bracketed hyphen indicating attachment of the side-chain.
 7. A polymer according to claim 1, which is a polyester.
 8. A polymer according to claim 1, wherein the perfluorocarbon group has 6 to 20 C atoms.
 9. A polymer according to claim 1, wherein either the backbone or side chain includes a hydrocarbon unit of 6 to 20 C atoms.
 10. A polymer according to claim 1, which has liquid crystalline properties.
 11. A substrate coated with a polymer according to claim
 1. 12. A process for preparing a partially fluorinated polymer which comprises reacting together corresponding compounds of the formulae

    Y.sup.1 --hc.sup.1 --Z(fc)--hc.sup.2 --Y.sup.1 and Y.sup.2 --hc--Y.sup.2 or Y.sup.2 --fc.sup.1 --Y.sup.2

    or Y.sup.1 --hc.sup.1 --Z(hc)--hc.sup.2 --Y.sup.1 and Y.sup.2 --fc--Y.sup.2

wherein Y¹ and Y² are mutually-reactive functional groups, on or within the hc or fc to which they are shown attached, that together form X¹ and X² in a polymer having one of the following formulas:

    --X.sup.1 --hc.sup.1 Z(hc)--hc.sup.2 --X.sup.2 --fc-- and

    --X.sup.1 --hc.sup.1 Z(fc)--hc.sup.2 --X.sup.2 --hc--

in which X¹ and X² are selected from the group of polymer forming linkages consisting of COO, OOC, CONH, and NHCO, Z is selected from the group consisting of --N--(SO₂ --)--; --CH(--)-- and --CH(CH₂ --)--; fc is a perfluorocarbon moiety having at least 4 carbon atoms; hc, hc¹ and hc² are hydrocarbon moieties. 